An ongoing clinical trial has been formulated to assess the therapeutic efficacy of oral amiodarone in patients with hypertrophic cardiomyopathy and either refractory cardiac symptoms or patients who are at high risk for sudden cardiac death. Over the past year, we have completed a study which now includes 72 patients with hypertrophic cardiomyopathy (41 plus or minus 14 years) as part of two protocols: Group 1 - patients with refractory cardiac symptoms (n=50) and Group 2 - patients who are at high risk for sudden death (n=22). Despite improved symptoms in Group 1 patients, and reduced ventricular arrhythmias in Group 1 and 2 patients, during the follow-up period (662plus or minus 273 days), 8 patients had sudden cardiac death (cummulative survival=88%). Sudden death appeared to occur early after instituting amiodarone treatment in patients with severe cardiac symptoms, and later in patients with high risk variables for sudden cardiac death. Unfortunately, we conclude that amiodarone does not prevent and may increase sudden cardiac death in certain subsets of patients with hypertrophic cardiomyopathy.